High power electron tube



w. P. BENNETT 2,817,031

HIGH FOWER ELECTRON TUBE Dec. 17, 1957 Filed April 1. 1953 3 Sheets-Sheet 1 E EN E E \N E. Q 3 M R wm EN I Q A E E E E N E. \m. E Q .E l. 3A w \wfl Wlwww h N E v E 5% f k\ E Q I INVENTOR.

Dec. 17, 1957 w. P. BENNETT 2,817,031

HIGH POWER ELECTRON TUBE Filed April 1. 1953 s SheetsSheet 2 I NVE NTOR.

llig falffic v ATTORNEY W. P. BENNETT HIGH POWER ELECTRON TUBE Dec.'17,' 1957 3 Sheets-Sheet 3 Filed April 1. 1953 NVENTOR.

- rather than by the required heat dissipation.

United States Patent HIGH POWER ELECTRON TUBE Wilfred P. Bennett, Lancaster, Pa assignor to Radio Corporation of America, a corporation of Delaware Application April 1, 1953, Serial No. 346,201

29 Claims. (Cl. 313-32) My present invention relates to high power tubes. and more particularly to such tubes designed for operation with a useful output ranging from 1,000 watts to about 10,000 watts at a high frequency.

Numerous problems are encountered in the construction of high power tubes for operation at high frequencies. The electrodes and other elements within the vacuum enclosure form a substantial part of the high frequency circuit in such devices. Thus, while it is desirable to pro vide a tube capable of a large power output. at frequencies commensurate with television broadcast practice, the size of the device and the components thereof forming the high frequency circuit is determined in the main by the upper frequency at which it is desired to operate the tube Interelectrode spacings must be small to permit attainment of the small electron transit time required for operation at such elevated frequencies. Furthermore, the high current densities required to obtain the desired high. power necessitates an electrode arrangement and configuration which among other things minimizes electron collection by electrodes other than the anode and which favors substantially equal transit times for simultaneously emitted electrons.

The principal objects of my invention include theprovision of a high power tube capable of about 10,000 watts output at high frequencies having high gain at such high frequencies, and which is adapted to. be, modulated over a very wide range of modulation frequencies, such as used in television.

A more specific object is the provision of an electron tube for operation With high power output in which mechanical stability and. heat dissipation are efliciently accomplished.

Another object is the provision of such a device having an electrode configuration which on the one hand permits efficient operation atv high frequencies and on the other hand facilitates eflicient heat dissipation.

Still another object is the provision of such a device in which the input and output circuit elements are eiiectively shielded one from the other and in which internal feed back is minimized.

Yet another object is the provision of such a device which, while incorporating precise close electrode spacings, comprises parts which may be readily manufactured and assembled in an array which, during operation, is electrically and mechanically stable.

In accordance with my invention, I provide an electron tube which physically contains a cathode, control grid and screen grid electrodes, each comprising a plurality of discrete elements all mounted symmetrically with respect to one anode with the elements in each electrode array electrically tied together and operated as one. I preferably utilize a centrally mounted anode having its lead extending axially at one end with the control grid lead extending axially in the opposite direction at the other end. A massive annular screen grid support block surrounds the active electron region including the cathode,

ice

control grid, active screen grid portions, and anode. The screen grid with its appurtenances completely shields the control grid from the anode, and the input and output circuits are completely separated.

My invention, as well as further objects thereof, will be best understood by reference to the following description taken in connection with the accompanying drawing in which:

Figure 1 is a sectional view of an electron tube constructed in accordance with my invention;

Figures 2, 3 and 4 are sectional views taken. through the lines 2-2, 3--3 and 44, respectively, of Figure 1;

Figure 5 is a perspective view on a still further enlarged scale of a pair of control grids;

Figure 6 is an enlarged elevational view of a single cathode element;

Figure 7 is a perspective view on an enlarged scale of a portion of the screen grid assembly;

Figure 8 is a fragmentary sectional View along line 88 of Figure 4 with the device rotated on its vertical axis to show another portion thereof other than that shown in Figure 4;

Figure 9 is a sectional view along the line 9-9 of Figure 8; and

Figure 10 is a fragmentary sectional view of another form of grid structure.

Referring now to Figures l 4 of the drawings in detail, it is seen that an electron tube 10 according to one embodiment of this invention comprises a cathode 11, a control electrode or grid 12, a screen electrode or grid 13 and an anode 14 arranged in that sequence. Each of the cathode, control grid and screen grid electrodes includes a plurality of separate elements all spaced in annular arrays about the centrally located anode. In effect, a plurality of elemental tetrodes are arranged about a central axis in such manner as to permit a high degree of physical and electrical stability while operating with high current density at elevated frequencies.

The nature of the electrode arrays is best briefly described in connection with Figure 3. Each cathode ele' ment 11' is surrounded by a control electrode element 12. Each screen electrode element 13 with its electrically continuous supporting parts is seen in turn to surround an individual cathode element 11 and control electrode element 12. As will be more fully pointed out herein below, the screen electrode wires 15 of each screen grid element 13 are supported by a pair of side rods 16, which in turn are connected to a screen grid support member 17. Each screen grid support member 17 is joined to a pair of vanes 17 which extend radially outward into slots formed in a screen grid block or ring 13. The vanes 17' together with the block or ring 18 form a plurality of channels 17 around the anode 14. As is apparent from Figure 3, each elemental tetrode includes the foregoing elements or electrodes with the screen grid element 13' completely enclosing a control grid 12 and a cathode element 11, while anode 14" is located on the radially inward side of screen grid 13' and spaced therefrom. The screen grid wires 15 of each screen grid element 13 extend across the channel 17 of that element. in the particu lar embodiment of my invention now being described, a plurality of such elemental tetrodes have been arranged in an annular array in order to take advantage of the electrical and physical symmetry which such an arrangement; makes possible. Because of the high power and high frequency at which it is desirable for such a device to be operated, such symmetry, as well as stability, are extremely important.

With the foregoing electrode arrangement in mind, it Will now be convenient to refer to Figure 1 wherein is shown a cross sectional view of electron tube 10 constructed in accordance with my invention. Cathode 11 is supported from a pair of spaced apart annular members 19 and 2.1), each of which is provided with a relatively large central aperture extending therethrough. The lower cathode support member or cathode header 19, as viewed in Figure 1, has an inwardly extending overhanging lip 19 (Figure 2) having a plurality of slots formed therein, which slots extend in an annular spaced array surroundmg the aperture in member 19. As may be seen in Figure 1, the under surface of lip 19' has V-shaped grooves formed therein which, as will be more fully described, serve to position and locate the lower ends of the cathode elements. Cathode header or annular member 19 has a coolant passageway 21 formed therein into which a coolant such as water is introduced to provide highly elficient heat dissipation from header 19.

A tubular member 22 is sealed to the inwardly preented surface of cathode header member 19 and forms a downwardly extending flange, the lower portion 22 of which is turned back upon itself to form an annular coolant channel 23. A grid support disc 24 of substantial thickness and having good heat and electrical conducting properties extends transversely within tubular member 22 and is co-axial with the same. The grid support disc 24 is joined at its outer periphery to the rim portion of a cup-shaped member 25. Cup-shaped member 25 in turn is supported from tubular member 22 by means of an insulating seal indicated generally at 26. The base of cupshaped member 25 is apertured to receive a tubular connector 27 having two bores 28, 29 formed therethrough. A tubular member 30, communicating with bore 28, serves as a coolant inlet pipe while bore 29 serves as an exit passageway for the circulating coolant. It is seen then that coolant is delivered through tubular member 30 to adjacent the under surface of grid support disc 24 and circulates along surfaces of both members joined through seal 26.

Seated on cathode header member 19 is the massive screen grid ring 18 with apertured mica disc 31 interposed to afford direct current insulation. Another apertured mica disc 32 serves to space and insulate upper cathode support member 20 from screen gn'd ring 18. Cathode support member 20 is also massive and formed of copper with an annular channel 33 (Figure 8) formed therein for receiving a coolant. A shoulder formed adjacent the inner periphery of member 20 has an upwardly disposed surface 20' (Figure 4) formed at an angle with respect to the horizontal as viewed in Figure 1. As most clearly shown in Figure 4, a pair of pipes 34 are connected to the under surface of member 20 and open into channel 33 on opposite sides of partition 35. Shoulder 20' is tapped to receive an annular array of bolts 36 which are alined with, and equal in number to, the aforementioned slots formed in the lip 19' of cathode header 19. A plurality of resilient members or springs 37 are provided, each being connected by one of the bolts 36 to shoulder 20. Resilient members 37 may be of suitable spring steel or the like clad with high conductivity material such as copper. As is apparent in Figure 1, each resilient member 37 extends over the central aperture of members 18, 19 and 20 and has a slot 37' (Figure 4) alined with one of the slots formed in lip 19'. The bifurcated innermost portion of each resilient member 37 is permanently deformed into a substantially V-shaped groove. As most clearly shown in Figure 6, each of the cathode elements 11 are elongated members, the end portions 38 and 39 of which have outwardly extending shoulders joined to the main body portion by reduced shank portions 40, 41. As most clearly shown in Figure 1, each of the elements of the cathode 11 is quick removably clipped in place between the alined V-shaped hooks formed on resilient members 37 and lip 19'. Each of the cathode elements 11' is formed of refractory material such as tungsten or tantalum or the like. When tantalum is utilized it is coated with thoria 42 on only one surface thereof as clearly shown in the sectional view thereof included in Figure 6. It should be understood that cathode elements 11' are physically connected solely by means of the V-shaped hooks to the cathode support members. At the upper end of the array, as viewed in Figure 1, the connection is completed by means of resilient members 37. At the lower portion of the array the quick detachable connection is made directly to cathode header 19. No other connection or contact is made to the cathode elements 11. In addition the aforementioned support members constitute the electrical leads thereto as well. A tubular member 43 connected to the under surface of cathode header 19 affords a convenient means for connecting the cathode to ground for grounded cathode type of operation or forms part of the return circuit for the oathode. Additionally, tubular member 43 provides inlet channels for the liquid coolant which flows in channels 21 and 23.

Another tubular member 44, somewhat similar to tubular member 43, is also supported from cathode header member 19 in registration with aperture 45. Tubular member 44 is joined to cathode header member 19 and insulated therefrom by an insulating collar 46 of glass or the like. Two bores formed in the externally threaded end cap 47 communicate with the interior of hollow tubular members 48, the upper portions of which (Figure 3) are connected to screen grid ring 18 as will be more fully described herein below. End cap 47 and tubular members 48 serve as the lead-in for screen grid 13 and form part of the vacuum envelope of the tube.

As has been previously pointed out, screen grid ring 18 is positioned between, and insulated from, cathode header 19 and the upper cathode annular support member 20. As shown in Figure 1, screen grid ring 18 is conveniently made of two L-shaped copper members sealed together in such manner as to leave an annular channel 49 adjacent the innermost surface of screen grid ring 18. Tubular members 48, as most clearly shown in Figure 3, are connected to screen grid ring 18, each communicating with channel 49 on opposite sides of partition 50. Thus, it is apparent that one tubular member 48 may serve as an inlet conductor for the liquid coolant, while the other member 48 serves as the outlet conductor. Tubular members 48 also function as the electrical lead-ins to screen grid ring 18 and screen grid 13. Still referring to Figure 3, it is seen that the radially innermost portion of screen grid ring 18 forms one of the walls of channel 49 and is thus bathed in coolant during operation of the device. Each of the end portions of vanes 17 of windowed screen grid support members 17 extends radially outward into a slot formed in screen grid ring 18 and is joined thereto by brazing or the like.

As most clearly shown in Figure 7 screen grid support members 17 are elongated sheet metal conductive members seated in slots formed in adjacent or opposed vanes 17' adjacent the inner ends thereof. A window or aperture 53, rectangular in shape as shown, is formed in each support member 17. Disc 55, which may be somewhat dished. functions as a shield between the anode structure and the control electrode structure. Peripheral. portion 54 of disc 55 is turned upward and brazed to each of the screen supports 17. A pair of side rods 16 (Figure 3) is provided for each of the screen grid support members, and each is mounted in the angles formed at the juncture of vanes 17' with member 17 Side rods 16 serve to support the individual screen gn'd wires 15. When desired, side rods 16 may be omitted and the screen grid wires 15 may be joined to radially outwardly turned portions of support member 17 and thus be supported across window 53.

As most clearly shown in Figure 1, the upper end portions 52 of screen grid support members 17 are each joined to an annular ring 57 which serves to interconnect and rigidity end portions 52. The opposite surfaces of end portions 52 are in contact with a radially inward presented surfaw 0f apertured disc 58. As will be more fully pointed out, apertured disc 58 is a conductivemetab lic member and functions as a circuit element inthe internal screen grid radio frequency by-pass to ground.

Referring now to Figures 8 and 9, a plurality of bolts 59 are passed through enlarged holes 20" in upper cathode support member 20 and threaded into tapped bores formed therefor in cathode header 19. These serve to rigidly mechanically connect upper cathode support member 20 and screen grid support ring 18 to header 19. While only one of the bolts 59 is shown, it is to be understood that a sufficient number are utilized to afford the desired me chanical interconnection of the various parts. are of a stainless steel having a thermal expansion which matches the thermal expansion of screen ring 18 and cathode support rings 19 and 20 at the temperature at which tube is processed or baked out so that they do not undergo such elongation at those elevated temperatures that the connection made thereby is impaired. Sandwiched between collar 60, retained by the head of bolt 59, and support member 20 is a pair of elongated mica insulators 61, between which is located elongated resilient member 62 of spring steel or the like. In the electron tube 10 constructed in accordance with my invention three bolts 59 and elongated resilient members 62 and six mica insulators 61 were provided. As will be seen, resilient members 62 serve to urge apertured disc 58 upwardly as viewed in the drawings.

Mica discs 31 and 32 are tightly clamped between cathode support members 19, 20 and screen grid block 18'. During temperature cycling the mica discs are subjected to great stress due to expansion of members 18, 19 and 20, which are copper. To avoid the possibility of a short circuit should the micas crack or break, they are each provided with several score lines so that such cracks will appear at predetermined locations. Screen grid block 18' is provided with grooves or recesses 18' (Fig. 8) which are in registration with each of the score lines. The additional spacing thus provided at those points insures against a direct current short circuit between member 18 on the one hand and members 19, 20 on the other.

Referring now to Figures 3 and 5, it is seen that control or grid electrode 12 includes a plurality of spaced wire wound elements 12, each supported by a pair of conductive side rods 64 which are in turn supported by a conductive support or standard 65. As viewed in Figure 5, standard 65 may be termed the lefthand member of a pair while standard 65' is the right-hand member. Thus, the control or grid electrode elements 12 with their associated side rods and standards are arranged in pairs for convenience in mounting on support disc 24. Grid support disc 24, as most clearly shown in Figure 1, is tapped to receive a plurality of bolts 66, one for each pair of control grid elements. The left and right hand standards, 65, 65 when arranged side by side have registering recesses 67 to permit the passage therebetween of one of the bolts 66. The side by side arrangement of the control grid support standards is most clearly shown in plan view in Figure 2. Annular plate 68, with slots 69 extending radially inward from the periphery thereof, serves as a convenient retainer for the array of control grid elements 12'. Slots 69 render the peripheral portions of plate 68 sufficiently flexible so that each pair of grid elements 12 may be accurately aligned independently of adjacent pairs. It should be further noted that the grid windings completely surround each of the spaced cathode elements 11. As was previously pointed out, the outer surface of grid support disc 24 is bathed in coolant during operation of the device. Side rods 64 as well as standard 65 are preferably of high conductivity metal, such as copper, not only with respect to electrical constructions but also to aiford eflicient heat transfer from the wire wound grid elements 12' to disc 24.

Referring now to Figure 1, the anode structure 14 is supported from anode header 70 which may be, as shown,

Bolts 59 an annular copper plate with a central opening therethrough. An annular ring shapedmember 71, which is U shaped in. cross-section, is. brazed on one side to the inner periphery of anode header '70 and on the other to an annular channeled member 72 which is of a suitable metallici alloy for'sealing with glass. A cup shaped anode support member 73, which is also. of suitable metal for sealing to glass, is supported from annular channeled member 72 by means. of: glass 74 sealed therebetween. It maybe noted: that channel 75 formed by annular member 72 serves as a coolant passageway for cooling the seal at. 76.

Channel 75, channel 23: and channel 21 are interconnected by inlet and outlet coolant conductors, as shown in Figure l, and receive coolant through the same tubular member 43. Since, during operation, these parts are at the same electrical potential, this may be conveniently accomplished.

As; clearly shown, the opening through anode header 70is sealed by cup shaped member 73 and the parts interconnected therebetween. The inwardly presented lip of cup shaped member 73 is conductively joined to and supports. an anode block 77 which in turn supports the hollow cylindrical anode 14. The upwardly presented base of cup shaped member 73. has a central aperture formed therethrough in registration with which is mounted a connector or tubular member 78. As was described in connection with connector 27, connector 78 is provided with inlet passageway 79 and outlet passageway 80. As shown, inlet passageway 79 is in registration with and joined to coolant conductor 81. Conductor 81 serves to lead coolant directly to channel 82, which is formed between anode block 77 and anode 14 and which communicates with the interior of cup shaped member 73. As shown, the surface of anode 14 forming part of channel 82 is spirally grooved to aid in creating turbulence in the coolant, thus enhancing the heat transfer.

A cylindrical member 83, preferably of copper, is sealed to anode header 70 adjacent the outer periphery thereof. Cylindrical member 83 carries a flange 84, while a similar flange 85 is carried by cathode header 19. Flanges 84 and 85 are substantially annular ring shaped members of steel which come into contact preferably only adjacent the outer periphery thereof where they are joined by an annular weld in vacuum tight relation. Flanges 84 and 85 are provided with a high conductivity coating such as silver.

Tube 10 is processed and the interior brought to a high vacuum in the usual way. A metallic tubulation (not shown) carried by cathode header 19 communicates with the interior of tube 10 through an opening formed in the cathode header. The metallic tubulation serves as a convenient means for attaching tube 10 to a vacuum pump 3 and is. pinched off to finally seal the envelope of tube 10.

A pre-processed getter such as shown and claimed in the application of Harbaugh and Garner, Serial Number 141,648, filed February 1, 1950, now U. S. Patent No. 2,640,945, may be conveniently utilized for gettering tube 10. Preferably a pre-processed getter capsule is mounted input leads.

on cathode header 19 in the space between screen grid support 18 and cylindrical member 83 with one or more frangible side arms extending down into the pinch-01f tubulation, the frangible tubulations being fractured when the tubulation is pinched off, thereby opening the interior fact that at no time do any of the input currents become intermixed with the output currents. For example, aperture disc 58, which is conductively connected to each of the screen electrode elements, forms one side of a coupling capacitor. The other side of the coupling capacitor is formed by anode header 70 across mica disc 86. Anode header 70 is conductively connected to cathode header 19, as previously described, which members form the low voltage or ground output terminal. Thus, the screen to anode capacity charging currents flow only in the output circuit and do not at any time flow in any part of the cathode circuit. Furthermore, this arrangement ensures that at no time do these charging currents flow in any circuit common to the input circuit of the tube. The other side of the output terminal is formed by the anode structure. It may be noted that screen electrode support 18 is also capacitively coupled to cathode header 19 through mica disc 31, the mica disc aifording direct current insulation. Mica disc 32 affords additional capacitive coupling between screen grid electrode support member 18 and the cathode support member 20, to which the cathode input leads 34 are connected. With the screen electrode to ground or cathode by-pass capacitors thus provided, tube is particularly well suited for the grounded screen, grounded cathode, grid driven type of operation.

In one such tube 10 constructed in accordance with my invention forty cathode elements 11', control grid elements 12', and screen grid elements 13' are each arranged about a centrally mounted anode 14. Cathode elements having an active surface .080 inch wide and .750 inch long were used. The space between the active surface of each of the cathode elements and its control grid was .015 inch while the space between the control and screen grids was .017 inch. The diameter of the screen grid array was 3.140 inches while that of the anode 2.640 inches. Such a tube, at 525 megacycles per second, has delivered a synchronizing peak power output for television broadcast of substantially 10,000 watts with an input of 25,000 to 30,000 watts.

A grid structure 90 as shown in Figure 10 may be utilized as for example as the control grid structure 12 when additional mechanical stability is desired. Such a structure also has improved grid cooling capabilities in view of the good thermal conduction path provided by each of the tubular members 91, which may be copper and which carry control grid wires 92. Annular foot or support member 93 is bolted to grid support disc 24 in place of standards 65, 65. Support member 93, which may be of such metal as copper, has a radially outwardly extending lip 93' in which is formed a plurality of holes one for each tubular member 91. A tubular member 91 is mounted in each of the holes of lip 93' as by brazing. When thus positioned, each of the tubular members 91 partially surrounds one of the cathode elements 11 which extend therethrough and are supported between header 19 and resilient members 37. Each of the tubular members 91 has a window or aperture formed therethrough located between the active cathode surface on the one side and the screen and anode electrodes on the other. Grid wires extend across the window of each tubular member 91 and are connected thereto.

Conveniently, all of the tubular members are accurately spaced about and connected to support member 93 before being mounted in tube 10. Accurate registration of the control grid elements 90 with the respective cathode elements 11' is thus readily attained. Such an arrangement facilitates assembly of the device as well as improving operation thereof.

From the foregoing, it is apparent that I have provided an electron tube capable of being operated at high frequencies at high power. While I have described my invention with respect to the particular tube shown, it is obvious that many variations may be made therein without departing from the scope of my invention. For example, while I have shown and described glass-to-metal 8 seals and a particularly advantageous arrangement therefor, other seal configurations as well as other components thereof may be utilized. In particular, seals of the ceramic-to-metal type may be utilized. Other changes within the skill of one familiar with such devices may readily be made. Therefore, it is desired that all modifications within the scope of the appended claims be included within my invention.

What I claim is:

1. An electron tube, comprising a cathode conductive support member, a second electrode conductive support member supported on said cathode support member and insulated therefrom as to direct current potentials, an anode spaced from said cathode and electrode support members, a plurality of spaced vanes conductively connected to said second electrode support member and extending toward said anode and forming a plurality of channels with said second electrode support member, an array of spaced cathode elements one in each of said channels and conductively connected to said cathode support member, and a plurality of conductive second electrode elements conductively connected to said vanes and extending across said channels intermediate said cathode elements and said anode.

2. An electron tube, comprising a plurality of spaced electrodes, a conductive support member supporting one of said electrodes, another of said electrodes comprising a plurality of spaced elements, a plurality of spaced conductive vanes conductively connected to said support member and extending toward a further one of said electrodes and forming a plurality of channels, one of said electrode elements extending in each of said channels, and said one electrode comprising a plurality of conductive elements conductively connected to said vanes and extending across said channels intermediate said other electrode and said further electrode.

3. An electron tube, comprising a cathode support member, an electrode support member supported on said cathode support member, a second cathode support member supported on said electrode support member, means insulating said electrode support member from said cathode support members as to direct current potential, an anode, a plurality of spaced vanes extending toward said anode and forming a plurality of channels with said electrode support member, an array of spaced cathode elements one in each of said channels and conductively connected to said cathode support members, and a plurality of wires extending across each of said channels and connected to the vanes forming said channels, said wires being located intermediate said cathode elements and said anode.

4. An electron tube, comprising an array of a plurality of spaced cathode elements, an anode spaced from said cathode elements, an array of a plurality of control electrode elements intermediate said cathode elements and said anode, there being a control electrode element for each of said cathode elements, each control electrode element surrounding its cathode element, an array of screen electrode elements intermediate said array of control electrode elements and said anode, a pair of spaced apart cathode support members conductively connected to each of said cathode elements and supporting the same, a screen electrode support member intermediate said cathode support members and supported thereby, said screen electrode support member being insulated from said cathode support members as to direct current potential, and a plurality of vane-like members conductively connected to said screen electrode support member and extending toward said anode, said vane-like members being disposed intermediate adjacent control electrode elements, said screen electrode elements extending between adjacent vane-like members.

5. An electron tube, comprising cathode, control, screen and anode electrodes in spaced relation, means supporting said screen electrode including a conductive germ-st support member, a plurality of conductive vanes conductively connected to saidsupport member and forming a plurality of channels open toward said anode, said cathode comprising a plurality of spaced elements one in each of said channels, said control electrode comprising a plurality of spaced elements one in each of said channels and having a portion intermediate the cathode element located in that channel and said anode, and said screen grid electrode comprising a plurality of conductive elements conductively connected to said vanes and extending across said channels intermediate said control electrode elements and said. anode.

6. An electron tube, comprising cathode, control, screen and anode electrodes spaced in that sequence, means supporting said screen electrode including a conductive support member having: a. coolant passageway formed therein, inlet and outlet means communicating with said passageway, a plurality of conductive vanes conductively connected to said support member and forming a plurality of channels open toward said anode, said cathode comprising a plurality of spaced elements one in each of said channels, said control electrode comprising aplurality of spaced elements one in. each of said channels and having a portion intermediate the cathode element located in that channel and said anode, and said screen electrode comprising a plurality of conductive elements conductively connected to said vanes and extending across said channels intermediate said control electrode elements and said anode.

7. An electron tube, comprising an envelope, an annular anode structure centrally located in saidenvelope, coaxial concentric screen, control and cathode electrodes spaced in that sequence about said anode, a cylindrical screen electrode conductive support member surrounding all of said electrodes, a plurality of spaced conductive vanes connected to the inner surface of said screen electrode support member and extending toward said anode, said vanes forming channels open toward said anode, said cathode and control electrodes each comprising an array of a plurality of spaced apart elements with one in each of said channels, and said screen electrode comprising a plurality of spaced. elements each extending across one of said channels and connected to the vanes forming said channel adjacent the ends thereof.

8. An electron tube as defined in claim 7 wherein the control electrode element in each of said channels surrounds the cathode element therein.

9. An electron tube as defined in claim 7 wherein said cylindrical screen electrode conductive support has a coolant passageway formed therein, and inlet and outlet coolant conductors communicating with said passageway.

10. An electron. tube, comprising cathode, control screen and anode electrodes spaced in that. sequence, means supporting said screen electrode including a con ductive support member, a plurality of conductive vanes connected to said support member and forming a plurality of channels open on one side, said cathode comprising a plurality of spaced elements one in each of said channels, a plurality of tubular members one in each of said channels and surrounding said cathode elements, each of said tubular members having an aperture formed through the wall' thereof, said control electrode comprising a plurality of spaced elements connected to each of said tubular members and extending across said apertures, and said screen electrode comprising a plurality of spaced elements connected to said vanes and extending across said channels intermediate said control electrode elements and said anode.

11. An electron tube, comprising an envelope, coaxial concentric cathode, grid, screen and anode electrodes spaced in that sequence in said envelope, a conductive cathode header forming a part of one side of said envelope, a grid support member joined to said cathode header but insulated therefrom and forming substantially the remainder of said side of said envelope; an annular conductive screen electrode support member supported on said cathode header but insulated therefrom as to direct current potentials, a plurality of spaced conductive vanes connected to said screen electrode support member and extending toward said anode, said vanes forming a plurality of channels open towards said anode, a second conductive cathode support member on said screen electrodes support member but insulated therefrom, said cathode electrode comprising a plurality of spaced cathode elements each connected to said cathode header and said second cathode support member, one of said cathode elements extending in each of said channels, said grid electrode comprising a plurality of spaced elements one for each of said cathode elements and surrounding the same, each of said grid elements being conductively connected to and supported by said grid support member, said screen electrode comprising a plurality of spaced elements each supported by a pair of said vanes forming one of said channels and extending across said channels intermediate said anode on one side and said grid and cathode on the other, a conductive anode header forming part of another side of said envelope and conductively connected to said cathode header, an anode support member sealed to but insulated from said anode header and forming substantially the remainder of said other side of said envelope, said anode being conductively connected to said anode support member, and a conductive member conductively connected to said screen electrode and capacitively coupled to said anode header.

12. An electron tube as defined in claim 11 wherein said cathode, grid, screen and anode electrode support members each has a coolant channel formed therein, and inlet and outlet members communicating with said channels.

13. An electron tube as defined in claim 11 wherein a shield connected to said vanes extends intermediate said anode and anode support member on the one hand and said grid support member on the other hand.

14. An electron tube, comprising an envelope, a cylindrical anode structure substantially centrally located in said envelope, coaxial concentric screen, control and cathode electrodes mounted in that sequence about said anode, an annular conductive screen electrode support member coaxial with said electrodes and surrounding the same, a plurality of spaced conductive vanes on said screen electrode support member and extending radially inwardly toward said anode, said vanes forming channels open toward said anode, opposed anode and cathode conductive header members forming portions of opposite sides of said envelope, an anode support insulatedly sealed through said anode header and supporting said anode, a control electrode support insulatedly sealed through said cathode header and supporting said control electrode, said cathode header being insulated from said screen electrode support as to direct current potential and supporting the same, a cathode support member insulated from said screen electrode support as to direct current potential and supported thereon, said cathode comprising a plurality of spaced elements one extending in each of said channels and connected adjacent one end to said said cathode header and adjacent the other end to said cathode support member, said control electrode comprising a plurality of spaced elements one for each of said cathode elements and surrounding the same, said control electrode elements being supported by said control electrode support, a plurality of screen electrode elements one for each of said channels and extending across the same intermediate said control elements and said anode and connected to said vanes, and an annular conductive member conductively connected to said screen electrode and capacitively coupled to said anode header, said annular conductive member being supported on but insulated from said cathode support member.

15. An electron tube as defined in claim 14 wherein resilient means on said cathode s'l'lpp'ort member urge 1 1 said annular conductive member toward said anode header.

16. An electron tube as defined in claim 14 wherein a plurality of conductive resilient members one for each of said cathode elements is conductively connected to and supported by said cathode support member, one end portion of each of said resilient members being bifurcated and over-hanging one of said channels and quick detachably engaging one of said cathode elements adjacent one end thereof, and said cathode header having a lip underlying said channels with a notch formed therein in registration with the bifurcated portion of each of said resilient members, the other end of each of said cathode elements being quick detachably engaged with said lip through the registering notch.

17. An electrode structure, comprising a conductive support member, a plurality of spaced conductive vanes conductively connected to one surface of said support member and extending therefrom, and a plurality of electrode elements conductively connected to said vanes adjacent the free ends thereof and extending across the space between adjacent Ones of said vanes, said supporting member and said vanes and said electrode elements constituting sides of a channel.

18. An electrode structure, comprising a relatively massive tubular block of conductive material having a coolant passageway formed therein, a plurality of spaced conductive vanes conductively connected to said block and extending therefrom, and a plurality of electrode elements conductively connected to said vanes adjacent the free ends thereof and extending across the space between adjacent ones of said vanes, said block and said vanes and said electrode elements constituting sides of a channel.

19. An electrode structure, comprising a support member having a bore formed therein, a plurality of conductive vanes connected to said support member in spaced apart relation and extending into said bore, said vanes and said support member forming a plurality of channels opening into said bore, and a plurality of electrode elements one extending across each of said channels and connected to the vanes forming the channel adjacent the ends thereof.

20. An electrode structure, comprising an annular support member having an axial bore therein as well as a coolant passageway for cooling the surface of said member defining said bore, a plurality of vanes connected to said support member and extending into said bore, said vanes and said support member forming a plurality of channels opening into said bore, opposed surfaces of said vanes having alined slots formed therein adjacent the ends thereof, and a plurality of electrode elements one extending across each of said channels and sealed in said alined slots.

21. An electrode structure, comprising a support member, an array of a plurality of tubular members connected to said support member, each of said tubular members having an aperture formed through the wall thereof, and electrode elements connected to each of said tubular members and extending across said apertures.

22. An electrode structure, comprising an electrically and thermally conductive support member, an array of a plurality of electrically and thermally conductive tubular members connected to said support member, each of said tubular members having an aperture formed through the wall thereof, and electrode elements connected to each of said tubular members and extending across said apertures.

23. An electrode structure, comprising an annular support member having a circular array of holes formed therein adjacent the periphery thereof, a plurality of tubular support members one sealed in each of said holes and connected to said annular support member, each of said tubular support members having an'aperture formed '12 through the wall thereof, and electrode elements extending across each of said apertures and connected to said tubular support members.

24. An electron tube, comprising an envelope with a conductive casing forming the major portion thereof, said conductive casing including a pair of opposed conductive members each having an opening formed therethrough, said openings being in opposed relation, a plurality of spaced electrodes in said envelope, a first conductive support for one of said electrodes insulatedly sealed through one of said openings and conductively connected to said electrode, a second conductive support for a second electrode insulatedly sealed through the other of said openings and conductively connected to said second electrode, a third conductive support for a third electrode conductively connected to one of said conductive members, and to said third electrode, and a fourth conductive support for a fourth electrode insulated as to direct current potential from said casing and conductive members but closely capacitively coupled thereto.

25. An electron tube, comprising an envelope with a tubular conductive casing forming a portion of said envelope, a pair of conductive members each having an opening formed therethrough and closing opposite ends of said casing with said openings alined, cathode, control, screen and anode electrodes in said envelope, a conductive anode support insulatedly sealed through one of said openings and closing the same, a conductive control electrode support insulatedly sealed through the other of said openings, a conductive cathode support conductively connected to said cathode and to said casing, and a conductive screen electrode support insulated from said cathode support as to direct current potential but closely capacitively coupled thereto and to said casing, there being a low impedance radio frequency path between said screen electrode on the one hand and said cathode and easing on the other hand.

26. An electron tube, comprising an envelope with a tubular conductive casing forming a portion of said envelope, a pair of conductive members each having an annular opening formed therethrough and closing opposite ends of said casing with said openings alined, concentric coaxial cathode, control, screen and anode electrodes spaced in that sequence in said envelope, a conductive tubular anode support insulatedly sealed through one of said openings and closing the same, an annular conductive control electrode support insulatedly sealed through the other of said openings, a conductive cathode support connected to said cathode and to said casing, a conductive screen electrode support insulated from said cathode support as to direct current potential but closely capacitively coupled thereto and to said casing, there being a low impedance radio frequency path between said screen electrode on the one hand and said cathode and casing on the other hand, and said anode support and said control electrode support each having diameters sufficiently large to form low impedance radio frequency paths.

27. An electron tube, comprising a cathode, control, screen and anode electrodes spaced in that sequence, a cathode conductive support connected to and supporting said cathode, a screen electrode conductive support supported on said cathode support and closely coupled thereto with respect to alternating current potential but insulated therefrom with respect to direct current potenial, conducive members connected to said screen electrode support and extending toward said anode and forming a channel open toward said anode, said cathode extending in said channel, said screen electrode being supported across said channel by said screen electrode support and the conductive members connected thereto, and said control electrode extending in said channel intermediate said cathode and said anode.

28. An electron tube, comprising a cathode, control,

screen, and anode electrodes spaced in that sequence, a cathode conductive support member connected to said cathode and having a portion extending from said cathode away from said anode, a screen electrode conductive support member on the side of said cathode away from said anode and supported on said cathode support member, said screen support member being closely coupled to said cathode support member with respect to alternating current potentials, conductive members connected to said screen electrode support member and forming a channel open toward said anode, said cathode extending in said channel, said screen electrode being supported across said channel by said conductive members connected to said screen electrode support, and said control grid extending in said channel intermediate said cathode and screen electrode.

29. An electron tube, comprising a cathode, control, screen, and anode electrodes spaced in that sequence, a pair of spaced apart cathode conductive support mem- 14 bers connected to said cathode and each having a portion extending from said cathode away from said anode, a screen electrode conductive support member on the side of said cathode away from said anode and supported intermediate said spaced cathode support members and insulated therefrom, said screen electrode support member being closely coupled to said cathode support members with respect to alternating current potentials, and said screen electrode being conductively connected to and supported by said screen electrode support member.

References Cited in the file of this patent UNITED STATES PATENTS Re. 15,278 Langmuir Jan. 31, 1922 2,204,306 Harris June 11, 1940 2,512,858 Hegbar June 27, 1950 2,512,859 Smith June 27, 1950 2,727,177 Bailey et a1. Dec. 13, 1955 

